The invention is related to the field of using ultra low viscosity volatile fluids (ULWF) as lubricant for rolling element bearings in general, and in particular in a refrigeration compressor. In this connection, for instance a liquefied refrigerant is supplied from the condenser to the bearing space in the bearings. The refrigerant which enters the bearing space is at saturation condition and is sprayed onto the bearing races and the rolling elements. The pressure of the liquefied lubricant drops in this process, as a result of which some of the lubricant may evaporate. The remaining liquid lubricant is maintained at saturation level. Thus, despite the fact that ULVVF's are fluids with a low boiling point and low viscosity, studies have revealed that they are nevertheless able to produce a lubricant film.
However, it appears that an ULVVF lubricant film is very thin in comparison to an oil based lubricant film due to said low viscosity and also due to low pressure-viscosity coefficients. A further problem in this connection is that, more often than not, within the bearing boiling or flashing occurs of the ULWF's, such as refrigerants, which are used as lubricants. This is caused by a decrease of the pressure or by the addition of energy, such as caused by frictional heat. In those cases, the bearing will run dry in an intermittent fashion, depending on said pressure decrease or added energy. Furthermore, flashing or boiling can also lead to cavitation at the entrance or the exit of the rolling contacts in the bearing. As a result of these phenomena, high contact shear stresses will occur which in the end lead to a reduced bearing life.